Earth, Stars Meet at Rochester

Most scientists have long agreed that the reign of dinosaurs came to an end
when an asteroid or comet slammed into Earth about 65 million years ago.

Now, new research by a Rochester team led by Robert Poreda, associate professor
of earth and environmental sciences, is shedding light on a similar event that
may have helped pave the way for the great lizards' dominance.

By making sensitive measurements of helium and argon isotopes that could only
have arrived on Earth from outer space, Poreda-joined by scientists from the
University of Washington, NASA, and New York University-pinpointed a cataclysmic
impact about 251 million years ago.

Setting off a chain of volcanic eruptions that covered the planet in sediment,
ash, and carbon dioxide, the blast could account for why more than 90 percent
of marine animals and about 70 percent of land vertebrates disappeared during
the boundary between the Permian and Triassic (P/T) eras, an extinction so pronounced
it is known to scientists as "The Great Dying," the team argues.

Worth Noting

Cellist Guy Johnston '03E won the 2000 BBC Young Musicians competition,
earning an invitation to solo on opening night of the BBC Proms Festival
at London's Royal Albert Hall.

Violinist Boram Kang '04E won the top prize in the National Symphony
Orchestra Young Soloist competition held in Washington, D.C.

The same combination of events has been documented during the Cretaceous/Tertiary
(K/T) boundary, the time when dinosaurs disappeared.

"These two extinctions are like bookends for the age of the dinosaurs,"
Poreda says. "The P/T boundary helped to usher in the age of the dinosaurs,
and the K/T boundary snuffed it out."

The study, published in Science, was one of several new glimpses of the Earth
and the universe provided by Rochester scientists in the last year.

In a separate study, Arial Anbar, assistant professor of earth and environmental
sciences and of chemistry, provided evidence that even during the extraordinarily
violent era in Earth's early history, the young planet was hospitable enough
for microbes to survive.

Studying a time 4 billion years ago, when Earth was hit by asteroids so frequently
that scientists call the period the "Late Heavy Bombardment," Anbar
and his team determined that only rarely-perhaps once every 30 to 100 million
years-was the bombardment so severe that microbes would have had difficulty
surviving.

And in another view of the universe, a team of Rochester astrophysicists may
have discovered the mechanism behind planetary nebulae, the wispy clouds of
light that radiate from some dying stars.

In a paper published in the January 25 issue of Nature, University astrophysicists
John Thomas, Andrew Markiel, Hugh Van Horn, Adam Frank, and Eric Blackman suggest
that a magnetic dynamo-similar to the kind that produces storms on the sun-appears
to shape planetary nebulae.